<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <div id="app">
      <span v-if="isUser">
        <label for="username">用户账号</label>
        <input type="text" id="username" placeholder="用户账号" />
      </span>
      <span v-else>
        <label for="email">用户邮箱</label>
        <input type="text" id="email" placeholder="用户邮箱" />
      </span>
      <button @click="isUser = ! isUser">切换类型</button>
    </div>

    <script src="../js/vue.js"></script>

    <script>
      const app = new Vue({
        el: "#app",
        data: {
          isUser: true,
        },
      });
    </script>
  </body>
</html>
